You can't! Applications' windows can't hide w/o dock. There's no place
to hide.

Of course you can, just open an app and try it. Appicons for

no, I didn't mean what actually happen :D

applications that are not docked will appear at the bottom of the
screen (along with mini-windows) which servers as sort of a taskbar,
like in this screenshot:
http://www120.pair.com/mccarthy/nextstep/intro.htmld/desktop1.gif
I have a feeling that you are familiar with the Aqua interface, but not
NeXTstep, here is an intro:

well.. I was in wmaker core for years. I think understand the point but
I didn't mean that..
er.. what should I say? it's like, from the shot, only if the dock.app
is running, the

appicons will appear at the bottom left not attaching to the dock... I mean,
it would be easier if each app don't have to maintain their own app icon

and one app can centralize all control over app icon which should be
simpler.